Method for measurement of ionized calcium

- Kyowa Medex Co., Ltd.

The present invention relates to a method for quantitatively determining ionized calcium in a sample by using a phospholipase, which comprises carrying out an enzyme reaction with the phospholipase in a buffer comprising a nitrogen heterocycle-binding sulfonic acid having a pK ranging 6.6 to 7.6 or a salt thereof.According to the method of the invention, the amount of ionized calcium in a sample, such as serum, can be accurately determined.

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Claims

1. A method for quantitatively determining ionized calcium, which comprises the steps of:

selecting a sample;
carrying out an enzyme reaction with a phospholipase in a buffer comprising a nitrogen heterocycle-binding sulfonic acid selected from the group consisting of N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid, 3-(N-morpholino) propanesulfonic acid, 1,2-N, N'-bis(N",N'"-di(2-sulfoethyl)piperazino)ethane, and a salt thereof;
quantitatively determining a reaction product of said enzyme reaction; and
correlating an amount of said reaction product with an amount of ionized calcium in said sample.

2. The method of claim 1 wherein the nitrogen heterocycle-binding sulfonic acid is N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid, 3-(N-morpholino) propanesulfonic acid, or a salt thereof.

Referenced Cited
U.S. Patent Documents
4761369 August 2, 1988 Steinman
4806486 February 21, 1989 Sprokholt et al.
5384247 January 24, 1995 Berry et al.
Foreign Patent Documents
4023999 January 1992 JPX
Other references
  • Stryer, "Biochemistry", p. 39, 1975. Month not available.
Patent History
Patent number: 5840512
Type: Grant
Filed: Apr 3, 1996
Date of Patent: Nov 24, 1998
Assignee: Kyowa Medex Co., Ltd. (Tokyo)
Inventors: Toshio Tadano (Shizuoka), Akira Miike (Shizuoka), Norihiko Kayahara (Kanagawa), Jun Umemoto (Hyogo)
Primary Examiner: Louise Leary
Law Firm: Fitzpatrick, Cella, Harper & Scinto
Application Number: 8/553,512